Phytophthora Root Rot on Fir Research Findings from North Carolina and Beyond John Frampton Professor & Christmas Tree Geneticist Department of Forestry & Natural Resources North Carolina State University CTFANY 2018 Winter Convention Syracuse January 19th
Presentation Outline Ø Background Information Ø Screening for resistance to Phytophthora cinnamomi Ø Other Phytophthora species Ø Strategies
Presentation Outline Ø Background Information Ø Screening for resistance to Phytophthora cinnamomi Ø Other Phytophthora species Ø Strategies
North Carolina’s Christmas Tree Industry 2 nd ranked state in U.S. 5-6 million trees harvested annually $100+ million wholesale value realized annually 2,500+ Christmas tree growers 98%+ of the harvested Christmas trees are Fraser fir produced in the western mountainous portion of the state 80%+ of the Fraser fir production is wholesale and shipped country-wide
North Carolina’s Christmas Tree Industry Species List Fraser fir (Abies fraseri) ------------------------------------------------------------------------------------- Virginia pine (Pinus virginiana) Eastern white pine (Pinus strobus) Eastern redcedar (Juniperus virginiana) Leyland cypress (x Cupressocyparis leylandii 'Leighton Green' ) Arizona cypress (Cupressus arizonica var. glabra 'Carolina Sapphire' & 'Clemson Greenspire' ) Atlantic white cedar (Chamaecyparis thyoides) Various spruces (Picea spp. )
Phytophthora v Name is Greek for “plant destroyer” v Genus of water mold (Oomycetes) v About 100 species (and counting) v Can multiply exponentially v Many species have mating strains designated as A1 and A2 v Several spore stages v Zoospores infect conifer roots and have two unlike flagella to sense and swim toward host
Sporangium releasing zoospores. (Oregon State University) Electron micrograph of Phytophthora cinnamomi zoospores encysting. (Giles Hardy) Zoospore infection of host plant. (Jim Deacon)
Brief History of Phytophthora cinnamomi in the Southeast U.S. Early 19 th v Pc believed to be introduced on exotic flora Century imported through southern ports v Reports of American chestnut and chinkapin mortality from lower elevations due to a root disease 1 st definitive report of Pc in the U.S. on three 1930 rhododendron species Pc identified as cause of � ink disease � on 1932 American chestnuts 1940s Littleleaf emerged as important disease on shortleaf pine 1 st Report of Pc on Fraser fir in North Carolina 1963 1976-1977 Fraser fir survey – 10% of sites infested NC Christmas tree industry < 1 million trees Crandall, B.S., G.F. Gravatt and M.M. Ryan. 1945. 1997-1998 Fraser fir survey – 9% of sites infested Phytopathology 35:162-180. NC Christmas tree industry 6-7 million trees
Impact on Fraser Fir v Primarily caused by P. cinnamomi v Results in $6-9 million in revenue losses annually v Control with Subdue feasible in nursery beds v Site selection & clean planting stock are our only preventative measures for the field v No resistance found in Fraser fir although other fir species have some resistance
Presentation Outline Ø Background Information Ø Screening for resistance to Phytophthora cinnamomi Ø Other Phytophthora species Ø Strategies
Resistance Screening in Fraser Fir Complete mortality in two greenhouse inoculations studies: • 100 open-pollinated families from Fraser fir seed orchard from Roan Mountain (1999)
Resistance Screening in Fraser Fir Complete mortality in two greenhouse inoculations studies: • 100 open-pollinated families from Fraser fir seed orchard from Roan Mountain (1999) • 99 open-pollinated families from all six of provenances of Fraser fir (2003)
Resistance Screening in Fraser Fir v Little, if any resistance in Fraser fir v Other fir species may offer resistance
Variation in Resistance to P. cinnamomi among Abies Species Objectives: v Rank the relative resistance of fir species v Identify potential sources of fir resistance
The Genus Abies The True Firs v 39-55 Species – 2 nd largest genus in Pinaceae v Temperate and frigid regions v Sea-level to over 5,000 m elevation v Northern Hemisphere - 14 ° N to 67 ° N latitude Worldwide distribution of the genus Abies (Farjon 1990)
Methods v Grew seedlings in greenhouse for two or three years v Inoculated with rice grains colonized with P. cinnamomi v Placed into an outdoor lath house and recorded mortality every two weeks for a total of 16 weeks v 32 Abies species, 50 seed sources v 6,629 seedlings total
Mean A. bornmuelleriana 1.0 A. firma A. fraseri A. pindrow 0.8 Mortality (proportion) 0.6 0.4 0.2 0.0 0 2 4 6 8 10 12 Time from Inoculation (wks)
Species Mortality (%) A. holophylla 88.8 Variation among Abies Species A. guatamalensis 90.2 A. fabri 90.6 A. alba 91.3 Mortality A. ernestii 91.9 Species (%) A. fargesii 92.5 A. firma (momi) 11.3 A. delavayi 95.6 A. pindrow (pindrow, Himalayan) 30.0 A. bracteata 96.9 A. bornmuelleriana (Turkish) 61.3 A. procera 97.4 A. numidica 97.5 A. cilicica (Cilcican, Toros) 63.2 A. sachalinensis 97.5 A. siberica (Siberian) 68.8 A. grandis 98.4 A. borisii-regis (King Boris) 75.0 A. balsamea 98.6 A. lasiocarpa 98.7 A. nordmanniana (Nordmann) 77.0 A. amabilis 99.2 A. cephalonica (Greek) 82.5 A. georgei 99.4 A. chensiensis (Chinese) 82.5 A. koreana 99.4 A. veitchii 99.4 A. equi-trojani (Trojan) 84.2 A. fraseri 100.0 A. concolor (concolor, white) 84.4 A. magnifica 100.0 A. nephrolepis 100.0
Conclusions v Most fir species are highly susceptible to P. cinnamomi v Some resistance exits in the Mediterranean and central Asia regions v Momi and West Himalayan (pindrow) fir appear to be relatively resistant
Caveats v Technique may overlook some types of resistance Ø Young trees Ø Severe disease conditions § Roots confined § High inoculum load § Continuously wet medium v Some mortality may not be due to Phytophthora v Limited sampling of provenances within species
Three Most Resistant Species 1 st Momi fir • – Poor Christmas tree quality – Breaks bud about one month earlier than Fraser fir 2 nd Pindrow fir • – No little known about this species – Very long needles – Does not produce many buds on branches • 3 rd Turkish fir – Closely related to Nordmann fir – Used as a Christmas tree in Europe & North America
Species Mortality (%) A. holophylla 88.8 A. guatamalensis 90.2 Mortality A. fabri 90.6 Species (%) A. alba 91.3 A. firma (momi) 11.3 A. ernestii 91.9 A. fargesii 92.5 A. pindrow (pindrow, Himalayan) 30.0 A. delavayi 95.6 A. bornmuelleriana (Turkish) 61.3 A. bracteata 96.9 A. cilicica (Cilcican, Toros) 63.2 A. procera 97.4 A. siberica (Siberian) 68.8 A. numidica 97.5 A. sachalinensis 97.5 A. borisii-regis (King Boris) 75.0 A. grandis 98.4 A. nordmanniana (Nordmann) 77.0 A. balsamea 98.6 A. cephalonica (Greek) 82.5 A. lasiocarpa 98.7 A. amabilis 99.2 A. chensiensis (Chinese) 82.5 A. georgei 99.4 A. equi-trojani (Trojan) 84.2 A. koreana 99.4 A. concolor (concolor, white) 84.4 A. veitchii 99.4 A. fraseri 100.0 A. magnifica 100.0 A. nephrolepis 100.0
Turkish & Trojan Fir Within Species Variation John Frampton and Fikret Isik
2005 Cone Collection Trip Black Sea Trojan Fir ( Abies equi-trojani ) 5 6 4 1 Kazdagi 2 Can Turkish Fir 2 ( Abies bornmulleriana ) 3 Uludag 3 4 Akyazi 1 5 Bolu 6 Safranbolu 6 Provenances 20 Trees/Provenance ----- ----------------------- 120 Trees Total
Turkish Fir Seeds Black Sea Trojan Fir ( Abies equi-trojani ) 4 5 6 33.3% 24.1% 1 Kazdagi 23.2% 2 2 Can 54.5% Turkish Fir ( Abies bornmulleriana ) 3 Uludag 3 50.8% 4 Akyazi 1 58.2% 5 Bolu 6 Safranbolu 6 Provenances 20 Trees/Provenance ----- ----------------------- 120 Trees Total
Geographic Pattern of Resistance v Although P. cinnamomi is not believed to be native to Turkey, other Phytophthora species are present (Balci and Halmschlager 2003) v Current or past contact with Phytophthora or other Oomycete species v Adaptation to environmental factors such as rainfall, soil temperature, and/or soil characteristics (e.g., texture)
100 90 80 70 Mortality (%) 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 Weeks after inoculation
Family Means for Mortality
Heritability Estimates 16 Weeks after Inoculation
Conclusions v Useful levels of resistance exist in Turkish and Trojan fir v Turkish fir has a higher frequency of resistance than Trojan fir v The frequency of resistance increase from west to east in the Trojan-Turkish fir range v Resistance is under strong genetic control
Genetic Basis of Phytophthora Resistance in Trojan fir Research of PhD graduate student, Will Kohlway Funded by USDA Specialty Crops Grant 2 Approaches Genotyping by Sequenceing (GBS) Genomic markers to select for resistant planting stock Does not address biological cause for resistance RNA-seq “Snap-shot” of cellular response against Phytophthora Study gene expression patterns Identifies genes important to root rot resistance
Presentation Outline Ø Background Information Ø Screening for resistance to Phytophthora cinnamomi Ø Other Phytophthora species Ø Strategies
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